"are you allowed to dye your hair after your are done with both?"
No, you are not. You are required to maintain military dress and appearance standards. Consider: You can be recalled to duty at any time. When you report, you can't show up with dyed hair. When you are recalled to your unit for a disaster, riot, or national emergency, you can't stop and take two hours to dye your hair back to meet regulations.
When you join the military, you are subject to control over certain aspects of your life that simply does not occur in the civilian world. You have to accept that as part of the deal. Joining the Guard means you are on-call 24/7/365 for both your country and your state. You have to be able to respond to that as-ordered. That includes meeting dress and appearance standards.