Jackson wanted to be unique and easily distinguishable and ultimately unique. While other Jedi would eventually show off different colored weapons, Mace Windu is the first to be shown without a green, blue, or red lightsaber.
Jackson reached out to Lucas to show interest in appearing in the prequels, but made some interesting requests before he accepted Windu's role. He was aware of his character's untimely demise later in the prequels and demanded an awesome and spectacular death. He didn't want to be killed off ingloriously “like some punk.”
Mace Windu was originally written into the original trilogy to play a major role such as the narrator, Princess Leia's brother or Luke Skywalker's friend. He was eventually cut out until Lucas wrote the prequels in 1994 where he plays a much different role in the Star Wars universe, and remains an incredibly memorable character today.
