4-4-2, low block on defense, with precise narrow shape and firm lines. Have 2-3 tall defenders, strong in the air, and put pressure on the crosses. Transition quickly to a flank overload, 2v1 or 3v2 on the left flank (depending who plays), by-pass the midfield, and avoid playing traditional channels in the build up. once in transition, use the quick forwards up top to take advantage of half spaces, or play balls over the top, depending on what strengths you have.
When defending the counter, make sure your midfield is strong enough, and have stamina enough to follow the top 3 back to break up the play. Don't over-commit on offensive corners.
I think Atletico is tactically strong, and will cause some concerns, if they can keep the shape and are physically strong enough to last the 90 (tall order). I don't know where Atletico will get the goals from though, that would be my main concern. If they can't threaten enough offensively, Liverpool can commit an extra midfielder to the attack and force goals.
Anyway, just my $0.02
ETA: A lot is going to depend on who is fit as well. If Liverpool can field a fit Henderson - Gini - Fabinho midfield, that will be tough for Atletico, as they have the work rate and tactical nous to withstand the flank overloads.