First you will need to ensure you have the Store Order Item Object within your list.
  1. The object can be found in Select Objects > Store> Store Order Item
  2. To add the Display Field, select the Display Fields Tab
  3. Click Select Fields
  4. Expand Store Order, Store Order Item, and mark the checkboxes for Prod Size and Prod Color (if needed)
  5. Click Select
  6. Save the List