[JWait]

If "more colors" is the only product option you have (i.e. no "size", "length", etc.) then it should be a simple matter of checking if the product has options in your products_tpl and displaying a "more colors" text or text variable.

Something like adding..
{if $active_modules.Product_Options ne ""}"More Colors"{/if} to your products_t.tpl might work.

Otherwise, just follow how product options are displayed on the product.tpl and product_details.tpl to find where it is determined where a product has options or not and add that to your products_t.tpl in the appropriate place with the appropriate text.