Major Themes:

UBRG (not W): Animate Lands
WBRG (not U): Artifact Tokens (Treasures, Clues, Blood, Food, Powerstones, Incubate, etc.)
WURG (not B): Equipment / Aggro
WUBG (not R): Poison
WUBR (not G): Enters for Creatures & Artifacts / Artifact Synergy

Minor Themes:

W: Blink / Bounce / Metalcraft
U: Affinity / Artifact Acceleration
B: Token Synergy / Graveyard Matters
R: Sacrifice
G: Anti Artifacts

Suggested Draft Decks:

WU: Turbo Affinity or Blink/Skies
BR: Sac with Token Fodder
GW/BG/WB: Poison Aggro
WB: Enters/GY Value
URx: Animate Lands with Tokens/Enters Value
WR: Eggs Aggro
UGx: Animate Lands or Turbo Artifact Ramp
BRG: Midrange Token Spam
WBGx: Midrange Poison
WBR/WUR/WUB: Blink/Enters/Graveyard-to-Hand
URGx: Animate Lands
UBR: Token Control