You can get easily dozends of orbs after vaultevents when you get as much vkeys as possible.
About The Labyrinth it’s always the same:
Green: shortest path
Blue: longer path
Red: dead end
Edit note to:
The reward usually unlocks if you have made it up to 90-100 in tuesday delves. For weekend delves it’s something between 200 and 230 afair. In both cases you should go for all rooms and get as much score as possible. You can either go for the highest multiplier or if you want really the absolute maximum in all cases you can use my OO Calc sheet I’ve created: