Change the parent item of a taxonomy to be a custom options page so the options page is highlighted when you are editing that taxonomy instead of the post type.

highlight-parent-admin-menu.php

<?php

	public function hooks() {
  	add_filter( 'parent_file', array( $this, 'highlight_admin_menu' ) );
  }

	public function highlight_admin_menu( $slug ) {
		global $parent_file;

		$screen = get_current_screen();
		if ( 'edit-taxonomy_name' == $screen->id ) {
			$parent_file = 'my_options_page_slug';
		}

		return $parent_file;
	}