Like Coachz, I rolled my own. Couldn't find anything as simple and easy as I wanted.
Created multiple colour buttons for my top toolbar. Each button triggers a custom script with a hard coded colour that works for whatever tracks or items you have selected at the time. Example below
Code:
if reaper.GetCursorContext2(true) == 0 then
-- Track(s) last selected
-- Get Reaper Command ID for SWS action "Set Selected Item(s) to Custom Color 1"
command_id = reaper.NamedCommandLookup("_SWS_TRACKCUSTCOL2")
reaper.Main_OnCommand(command_id,0)
reaper.Main_OnCommandEx(reaper.NamedCommandLookup( command_id), 0, 0)
--
elseif reaper.GetCursorContext2(true) == 1 then
-- Item(s) last selected
-- Get Reaper Command ID for SWS action "Set Selected Track(s) to Custom Color 1"
command_id = reaper.NamedCommandLookup("_SWS_ITEMCUSTCOL2")
reaper.Main_OnCommand(command_id,0)
reaper.Main_OnCommandEx(reaper.NamedCommandLookup( command_id), 0, 0)
--
end