I want to know if it is allowed for women to cut their hair or to color it?

All perfect praise be to Allaah, The Lord of the Worlds.  I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Basically, cutting a woman's hair for adornment is permissible as there is no evidence in the Quran and Hadeeth that prohibits this act provided that there is no resemblance to men or disbelieving women, in which case it would become forbidden. Ibn 'Abbaas and his father, narrated that, “The beloved Prophet Muhammad cursed men who make themselves resemble women and cursed women who make themselves resemble men.” [Al-Bukhari]

In fact, the evidences that prohibit imitation of the disbelievers are so many as to reach the level of being continuously narrated by a very large group such that it leaves no room for doubt.

As for coloring ones hair, then it is permissible but one should avoid black. If the changing of color is to imitate the disbelievers or to make it black, then it is impermissible. One may use any other color in order to attain a beautiful finish.

Allaah Knows best.