<form id="customsearch" method="get" action="<?php echo Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_LINK); ?>catalogsearch/advanced/result?">
<?php
    $advanceSearch = array(
        array(
            'attrib' => 'color',
            'selectName' => 'color[]',
            'labelName' => 'Color'
            ),
        array(
            'attrib' => 'style',
            'selectName' => 'style[]',
            'labelName' => 'Style'
            )
    );
    $html = '';
    $attributes = Mage::getModel('catalogsearch/advanced')->getAttributes();
    foreach ($advanceSearch as $as)
    {
        $html .= " <label for='as-" . $as['labelName'] . "'></label> <select id='as-" . $as['attrib'] . "' name='" . $as['selectName'] . "'><option value=''>All</option>";
        foreach ($attributes as $a)
        {
            if ($a->getAttributeCode() == $as['attrib'])
            {
                foreach ($a->getSource()->getAllOptions(false) as $option)
                {
                    $html .= "<option value='" . $option['value'] . "'>" . $option['label'] ."</option>";
                }
            }
        }
        $html .= "</select> ";
    }
    echo $html;
?>
<input type="submit" value="search">