Just put your tables to tabelas.dia file. Use http://projects.gnome.org/dia/ to open this file and organize your project

export_to_dia.php

<?php

/* File that you want to export */
$file = dirname(__FILE__).'table.dia';

/* Sample of table format */

$tables = array(
    'tablename' => array (
        'id'   => 'INT',
        'name' => 'VARCHAR(100)',
        'obs'  => 'TEXT',
    ),
    'person' => array (
        'id_person' => 'INT',
        'name'      => 'VARCHAR(100)',
    ),
);

ob_start();

print <<<EOF
<?xml version="1.0" encoding="UTF-8"?>
<dia:diagram xmlns:dia="http://www.lysator.liu.se/~alla/dia/">
  <dia:diagramdata>
    <dia:attribute name="background"><dia:color val="#ffffff"/></dia:attribute>
    <dia:attribute name="pagebreak"><dia:color val="#000099"/></dia:attribute>
    <dia:attribute name="paper">
      <dia:composite type="paper">
        <dia:attribute name="name"><dia:string>#A4#</dia:string></dia:attribute>
        <dia:attribute name="tmargin"><dia:real val="2.8222000598907471"/></dia:attribute>
        <dia:attribute name="bmargin"><dia:real val="2.8222000598907471"/></dia:attribute>
        <dia:attribute name="lmargin"><dia:real val="2.8222000598907471"/></dia:attribute>
        <dia:attribute name="rmargin"><dia:real val="2.8222000598907471"/></dia:attribute>
        <dia:attribute name="is_portrait"><dia:boolean val="true"/></dia:attribute>
        <dia:attribute name="scaling"><dia:real val="1"/></dia:attribute>
        <dia:attribute name="fitto"><dia:boolean val="false"/></dia:attribute>
      </dia:composite>
    </dia:attribute>
    <dia:attribute name="grid">
      <dia:composite type="grid">
        <dia:attribute name="width_x"><dia:real val="1"/></dia:attribute>
        <dia:attribute name="width_y"><dia:real val="1"/></dia:attribute>
        <dia:attribute name="visible_x"><dia:int val="1"/></dia:attribute>
        <dia:attribute name="visible_y"><dia:int val="1"/></dia:attribute>
        <dia:composite type="color"/>
      </dia:composite>
    </dia:attribute>
    <dia:attribute name="color"><dia:color val="#d8e5e5"/></dia:attribute>
    <dia:attribute name="guides">
      <dia:composite type="guides">
        <dia:attribute name="hguides"/>
        <dia:attribute name="vguides"/>
      </dia:composite>
    </dia:attribute>
  </dia:diagramdata>
  <dia:layer name="First Plan" visible="true" active="true">

EOF;

$x = 1;

foreach ($tables as $table => $attributes) {

$x++;

print <<<EOF

    <dia:object type="Database - Table" version="0" id="O0">
      <dia:attribute name="name"><dia:string>#$table#</dia:string></dia:attribute>
      <dia:attribute name="elem_corner"><dia:point val="0.5,$x"/></dia:attribute>

      <dia:attribute name="obj_pos"><dia:point val="2.2,1.2"/></dia:attribute>
      <dia:attribute name="obj_bb"><dia:rectangle val="1.2,1.2;7.12,3.1"/></dia:attribute>
      <dia:attribute name="meta"><dia:composite type="dict"/></dia:attribute>
      <dia:attribute name="elem_width"><dia:real val="5.9199999999999999"/></dia:attribute>
      <dia:attribute name="elem_height"><dia:real val="1.8999999999999999"/></dia:attribute>
      <dia:attribute name="text_colour"><dia:color val="#000000"/></dia:attribute>
      <dia:attribute name="line_colour"><dia:color val="#000000"/></dia:attribute>
      <dia:attribute name="fill_colour"><dia:color val="#ffffff"/></dia:attribute>
      <dia:attribute name="line_width"><dia:real val="0.10000000000000001"/></dia:attribute>
      <dia:attribute name="comment"><dia:string>##</dia:string></dia:attribute>
      <dia:attribute name="visible_comment"><dia:boolean val="false"/></dia:attribute>
      <dia:attribute name="tagging_comment"><dia:boolean val="false"/></dia:attribute>
      <dia:attribute name="underline_primary_key"><dia:boolean val="true"/></dia:attribute>
      <dia:attribute name="bold_primary_keys"><dia:boolean val="false"/></dia:attribute>
      <dia:attribute name="normal_font"><dia:font family="monospace" style="0" name="Courier"/></dia:attribute>
      <dia:attribute name="name_font"><dia:font family="sans" style="80" name="Helvetica-Bold"/></dia:attribute>
      <dia:attribute name="comment_font"><dia:font family="sans" style="0" name="Helvetica"/></dia:attribute>
      <dia:attribute name="normal_font_height"><dia:real val="0.80000000000000004"/></dia:attribute>
      <dia:attribute name="name_font_height"><dia:real val="0.69999999999999996"/></dia:attribute>
      <dia:attribute name="comment_font_height"><dia:real val="0.69999999999999996"/></dia:attribute>

      <dia:attribute name="attributes">

EOF;

foreach ($attributes as $attribute => $type) {

echo <<<EOF

        <dia:composite type="table_attribute">
          <dia:attribute name="name"><dia:string>#$attribute#</dia:string></dia:attribute>
          <dia:attribute name="type"><dia:string>#$type#</dia:string></dia:attribute>
          <dia:attribute name="comment"><dia:string>##</dia:string></dia:attribute>
          <dia:attribute name="primary_key"><dia:boolean val="false"/></dia:attribute>
          <dia:attribute name="nullable"><dia:boolean val="false"/></dia:attribute>
          <dia:attribute name="unique"><dia:boolean val="false"/></dia:attribute>
        </dia:composite>

EOF;

} // End of attributes

print <<<EOF

      </dia:attribute>
    </dia:object>

EOF;

}

print <<<EOF

  </dia:layer>
</dia:diagram>

EOF;


$content = ob_get_contents();
file_put_contents($file, $content);
ob_end_clean();