Multiple modulus calculations for looping background colours

mod_backgrounds.php

<?php
// $posts is some content to loop over and output. Perhaps 28 items.
// We want raindow coloured boxes so loop over 7 possible colours.
$posts_count = 0;
foreach ( $posts as $post ) :
	$colour = '';
	if ( $posts_count % 7 == 0 ) {
	    $colour = 'red';
	} elseif ( $posts_count % 7 == 1 ) {
	    $colour = 'orange';
	} elseif ( $posts_count % 7 == 2 ) {
	    $colour = 'yellow';
	} elseif ( $posts_count % 7 == 3 ) {
	    $colour = 'green';
	} elseif ( $posts_count % 7 == 4 ) {
	    $colour = 'blue';
	} elseif ( $posts_count % 7 == 5 ) {
	    $colour = 'indigo';
	} elseif ( $posts_count % 7 == 6 ) {
	    $colour = 'violet';
	}
	
	echo '<div class="' . $colour . '">' . $post . '</div>';

	$posts_count++;
endforeach;
?>