If you have acquired the 'Custom Fields per color' add-on module, the option 'Diff. per color' will be visible when you set up your Custom Fields. 

This allows you to set up which of your style custom fields should have different values per color.

To enable this option, click the checkbox the 'Diff. per color' on each of the three custom fields types.

When this option is sat it will be possible to give differentiated values for any specific custom field on a style - read more about it here.