Near the top of the raid window file (eq2ui_mainhud_raid.xml), look for this line:
<Data Name="13" Tag="ColorBkgOpac" Value="0.800" />
If you change the 0.800 to
1.000, the four colored background areas will be completely solid, which may be enough for you to differentiate the groups. If not, you can make the thin gray group borders brighter. Search for four instances of
Name="BkgFrame"
On each of these lines you can change Color="
#4F4A46" to a lighter color. For example
#FFFFFF will make the group borders white, which will definitely make it clear which group is which. If that's too bright, try
#888888 which is somewhere between white and the original dark gray. If you want to change the group background colors themselves, you can do that on the lines just below BkgFrame. Look for
Name="Bkg".
.