can your job make you dye your hair?

[angel]

im 17 i have black hair with Dark purple underneath i work where i have to have my hair ina pny tail so the purple underneath is seen but my pony tail overs most of it. i also ware a hat. i was sent home so i covered it with a black band. i been working now for over 3 weeks with the same manager. he even made funny comments about my hair. all managers are okay with it covered or not. i asked for saturday off, they wanted me to come in if i was in town early enough but i was not, i went into work the next day, i was told they see purple and not to return to work until its dyed. i have not bought a black hair net that will cover all the purple and take any bits in my Pony tail to cover even more. i live in arizona, is there a law on rights of how far an employee can push you? my hair been dyed like this since Dec 28, thanks