I am using a mid 2012 Mac Pro, I don't know what is needed so here's everything: 3.33 GHz 6-Core Intel Xeon processor, 6 GB 1333 MHz DDR3 ECC, ATI Radeon HD 5770 1024 MB with the most up to date Java. I'm having the same issue on an 09' Macbook Pro however.
I played Salem a few years ago and received an email the other day saying the game had been released. I was really bummed to learn about this issue. After an hour or two of reading forum posts and trying different color-change utilities with no success, I had to give up. As someone else said, I understand this issue may not be the Developers' fault at all, but I think we can all agree the user shouldn't have to make those kinds of changes to their system to play (and it's hard to say if that even solves this particular issue). It may be that it isn't even feasible for you guys to recreate/solve this bug, in which case it may be best to not say Salem can be played on Macs. It's lame to frustrate and waste the time of people who really want to play the game

Anyway I hope this doesn't come across as overly abrasive. Salem just seems right up my alley and I was really excited about playing. I do appreciate what you guys do. Goodluck!