This 540 card cube is designed with one priority in mind: Flexibility. Archetypes are generally focused around shards and wedges, rather than guilds, though that doesn't mean you should be drafting three or more colors every draft. This is simply a choice in design philosophy to allow each archetype to work better with each other and allow pivoting around during the draft to feel natural. Though I wouldn't fault you for dipping your toes into a third color. I mean, the fixing is there for a reason!

Esper: Cycling
Grixis: Discard
Jund: Big Value
Naya: Domain
Bant: Flicker
Abzan: Tiny Reanimator
Jeskai: Spellslinger
Sultai: Graveyard
Mardu: Sacrifice
Temur: Ramp