Custom Panel Background Color

Hi, I am new to the forums and am looking for some guidance on custom panels.

I have this panel with a bunch of buttons, and it’s getting hard to find specific buttons when working with it.

After searching through different forums I could not find how to edit the header or background color of a custom panel. The idea is to get to something similar to the image bellow.

Is it even possible to do that, and if not, do you have any suggestions on how to improve this readability problem?

Thank you for your time.