I've no idea how your coding skills are, but, my suggestions in pseudo code/logic; YOU turn it into real code
Use a table to store groups you want, then an if statement to check the table and if matched, draw.
my_groups_I_want_to_see = { "moderator", "admin" }
group = self:GetNWString("usergroup")
if table.HasValue( my_groups_I_want_to_see, group ) then draw.SimpleText(group, "DarkRPHUD2", pos.x + 80, pos.y - 26, Color( 0, 140, 210, 255 ) )
(table.HasValue is not really efficient for frame by frame drawing like this likely does..you find the faster methods)