The way these things work, Arsenal will probably end up getting paired with teams which they have played before.
Anyhow, here are the four groups of teams. Arsenal will play one from each of pots 2, 3 and 4.
Pot 1: AC Milan (ITA), Barcelona (ESP), Liverpool (ENG). Inter Milan (ITA), Arsenal (ENG), Real Madrid (ESP), Chelsea (ENG), Manchester United (ENG)
Pot 2: Valencia (ESP), Lyon (FRA), Porto (POR), Sevilla/AEK Athens (ESP/GRE), PSV Eindhoven (NED), Roma (ITA), Benfica (POR), Wereder Bremen (GER).
Pot 3: Celtic (SCO), Schalke (GER), Stuttgart (GER), Steaua Bucharest (ROM), CSKA Moscow (RUS), Sporting Lisbon (POR), Lazio (ITA), Marseille (FRA).
Pot 4: Rangers (SCO), Shakhtar Donetsk (UKR), Besiktas (TUR), Olympiacos (GRE), Dynamo Kiev (UKR), Fenerbahce (TUR), Slavia Prague (CZE), Rosenborg (NOR)
So perm any three from 24. In fact, there are only two potential opponents in pot 2 we haven’t played in recent seasons. For interesting trips, my personal choices would be Sevilla from pot 2, Steaua Bucharest from 3 and well… pot 4. Hmmm. An early away in Greece would be good for a bit of sunshine, although you’d have to watch out for pyromaniac property developers. Chances are we’ll be heading somewhere in the former Communist block.
What will happen? PSV, CSKA Moscow and one of the Ukraine sides. Just wait and see.