The grouping is decided upon by the Manufacturer SKU or Code in Retail Express. If these are the same it will group all of these products together. So you can decide in REX if you want colours together or separate. If you would like the product to appear in the eCommerce system as separate colours not all under same product with 2 sets of options you need to change REX.
The Translator cannot separate products once the product and their SKU’s have already been created in eCommerce. To re-create these products again in the fashion to match retail express you will need to remove these and get the Translator to re-create them.