- var_dump: documentation ( source)
- preg_match_all: documentation ( source)
<?php
$str = <<<HTML
<FONT FACE="League" SIZE="15" COLOR="#000000"><font COLOR="#ff00ff" SIZE="18"><b><font SIZE="23"><font SIZE="27"><font SIZE="23"><font SIZE="18"><font SIZE="23">Moet Flip make-up dragen? <br />Stem mee in de poll!!</font></font></font></font></font></b></font><br /></FONT>
HTML;
preg_match_all('/color\s*=\s*([\'"]?)#([0-9a-f])\1/i', $str, $matches);
var_dump($matches);