This one was easy, I knew exactly what I wanted to do!
I started with 2 coats of Purple Professional #32, then, on my accent nail, I placed some striping tape and then painted each remaining space with the rainbow colours. For this I used Kiko 334 (2 stripes), Sally Hansen Complete Salon Manicure Good to Grape, O.P.I Fly, Sally Hansen Hard as Nails Limewire, Sally Hansen Xtreme Wear Mellow Yellow, Basic #291 and Andreia #40 (2 stripes).
Some stripes don't look perfect, but I'm happy with this, I think it looks cute! xD