in the cart object, create a new calculation named "productName", set the data type to text and the calculation as:
[Name] .' Size '. [Size] .' Color '. [Color]
On the Check out page, open the server behaviors panel and double click the Authorize Transaction with PayPal express checkout, bind the item name setting the productName column from the cart.
the checkout wizard would add the Store Cart Summary and store Cart Details behaviors to the pp_confirm page. You can edit the store cart details behavior, and bind the Name column of the order details table to the productName cart column.