<div class="color-selection size-1">
    <div data-slug="blue" class="entry" style="color: #3481c7;"></div>
    <div data-slug="gray" class="entry" style="color: #eeeeee;"></div>
    <div data-slug="yellow" class="entry" style="color: #edb82c;"></div>
    <input id="pa_color" type="hidden" class="color_val" data-attribute_name="attribute_pa_color"
           name="attribute_pa_color" value="light-blue">
</div>

Все это находитсяв в single-product/add-to-cart/variable.php