To achieve this look, you’re going to have to entirely bleach out your hair. (If you’re not used to handling bleach, please see a professional in order to do it safely and evenly.) Now blend the tones by doing your hair in portions, from indigo, to green, to red and pink. Silver tones are also good. However, remember to keep the look pigmented and not pastel!
This process is very time consuming and could take up to four or five hours. The up keep is also tough. Touch ups are absolutely mandatory so that the colors don’t fade. Don’t feel entirely discouraged however–you can achieve the look more simply with wash out temporary dye if you want it for just one night. It won’t look as good but it’ll get a fun idea across.