Main product pic don’t switch in product list page

Hi guys, i can’t find the way to let the main pic of a product switch into the right color when selecting, It’s talking about the product list page where i show only the available colors of a product hiding the sizes: https://sportlifecastelnuovo.it/categoria-prodotto/donna/abbigliamento-donna/abbigliamento-trekking-donna/pantaloni-trekking-donna/

Please let me know when possible, thx!

Simo