I'm gonna make it more specific
Our loved and favorite Inkmatas hair color can be anything but she mainly chooses Yellow-green because she has an autograph from her favorite celebrity from Inkopolis plaza
Whitespace Inkmatas' hair is colored Red because she pleged her loyalty to bloodstone. Bloodstone magic makes hair turn red (most of the time) which is why if someone has their hair dyed red they'll have to go through a blood test.
Evil Inkmatas' hair is purple mainly because of the energy beams she can shoot out are also purple.
