Combination groups - Colour picker Module

[MalcolmPresta]

I'm using the colour picker module and my products are placed in groups with colours, however if the customer doesn't select a colour they can still select a non existent product and progress to checkout.  It needs a colour selected in order to be valid. When I looked up how to stop this happening it says I should select a different default however the default is set to an entire group so I can't select a different one. I hope that makes sense. Can anyone help?