Go in with a coherent strike package - fighters loaded with swarm missiles, gunships with torpedoes - catch the Diomedes with its jump drive cold, swarm it to overwhelm the fighter escort, and you'll be okay. Like all capships (back to World War II) or even modern-day tanks it's an incredibly potent platform if positioned correctly and supported well but it needs cover from the fighters/infantry.
Assuming it doesn't pull in a standby squadron from a GTVA carrier or an Aeolus/Deimos tag-team to save its arse.
Most of those tricks won't work too well for various reason (shoot it lots hits the 'bigship' flag; it's hard to lock torpedoes because of AAAf; the ship will be maneuvering so the fighterbay will move). You really have to go in as a team, but it's not an ubership. Just tactically well-leveraged.
All that aside, it's a strike corvette, designed either to hit the enemy (so it wouldn't be on the defensive and you might not have a strike package ready) or to provide flank security for GTVA gunlines (in which case it has a destroyer sortieing escorts.)
