Hi Stefan and thank you for taking the time to share a feature request.
Can you elaborate a little bit more about what you're looking for in terms of coloring row attributes when grouping is enabled? Screenshots with annotations help a lot!
This might not be what you're looking for exactly, but also be sure to check out the following forum post about coloring tags (which you can group by): Specific Tag Colors
Looking forward to hearing more about what you're looking for and if that other community post helps!
Mark