To change the cart icon background color add the below CSS code

.woocommerce.et-db #et-boc .et-l a.button.add_to_cart_button  {
    background-color: #e8a202  !important;
    border: 0 !important;
}

.woocommerce.et-db #et-boc .et-l .et_pb_shop .product .add_to_cart_button:after {
    color: #ffffff !important;
}