Hello,
take a look into 'hook_examples.lua' in the gamemode folder:
hook.Add( "GetScoreboardNameColor", "Name Color Example", function( ply )
if ply:IsUserGroup( "vip" ) then -- If the player is in the "vip" group
return Color( 255, 0, 0, 255 ) -- give the player a red name.
end
end )