WooCommerce Product Category Swatches

functions.php

<?php
function display_product_colors() {

    $colors = array();
    $options = get_post_meta(get_the_ID(), '_swatch_type_options', true);
    foreach($options as $option) {
        foreach($option as $item) {
            foreach($item as $att) {
                $colors[] = $att['color'];
            }
        }
    }
    $colors = array_unique($colors);
    foreach($colors as $color) { ?>
        <div class="archive-swatch" style="background-color:<?php echo $color; ?>"></div>
    <?php } ?>
    <style>
	    .archive-swatch {
	    	display: inline-block;
			width: 20px;
			height: 20px;
			outline: solid 1px #ccc;
		}
    </style>
    <?php

}
add_action('woocommerce_after_shop_loop_item', 'display_product_colors');