If it's been casted by an MD - it'll take 6-8 weeks no matter what you do. Here's where a true 'cheerleader' proves her worth by supporting her team-mates and helping them do a good job. If you mope & whine - you lose. And remember: You chose to jump off the cliff - now live with it and rise above it.
If your ankle was actually broken, there really is nothing you can do to speed up the healing in any meaningful way. Staying off the injury, taking the recommended calcium and vitamin d and physical therapy may be able to shave off a few days... But bones heal at pretty consistent paces. I know it sucks but it's just the way bones repair themselves. Plus with a fracture in your ankle you aren't just looking at the repair time. Often before you are re-permitted to do high impact activities you need to go through physical therapy AFTER the break is healed and BEFORE you can do anything else on it. Plus, breaks like this make you more prone to future injuries and fractures.
Feel better! Sorry I couldn't give more optimistic advice.
It would have been better to ask that question before you went diving. Now it will take as long as it takes to completely heel. Don't try pushing it or you could hurt it again. Then your heeling time would be even longer.