Here you go:
if SERVER then
function GodGroup( ply )
if ply:IsUserGroup("GroupNameHere") then -- Just place the name of whatever group you want goded here.
game.ConsoleCommand( "ulx god " ..ply:Nick().. " \n" )
Msg( "Granted " ..ply:Nick().. " Godmode \n" )
end
end
hook.Add( "PlayerSpawn", "GodGroup", GodGroup )
Not tested but should work. To use, just save it as "anything.lua" and place it in your server gmod_root/lua/autorun.
==EDIT==
Does ULib have a function like ULib.god(ply)?