Please add this to Theme Options => Custom CSS:
.single-product.woocommerce .yith-wcwl-add-to-wishlist a {
color: #fff !important;
border-color: #ed6d36 !important;
background: #ed6d36 !important;
}
.single-product.woocommerce .yith-wcwl-add-to-wishlist a:hover {
color: #ed6d36 !important;
border-color: #ccc !important;
background: #ccc !important;
}