here’s some more sensible colour guides for the rules lovers.
No more than 4 colours, not including black, greys and silver because they go with anything
you can put pretty much any 2 colours together and get away with it
with 3 saturated colours 2 of them should be adjacent in the colour wheel e.g. red – orange – yellow – green, cyan, blue, magenta, red ->
with 4 colours you need to 2×2 colour pairs as above but the chance of it looking a bit ravey increase dramatically.
Or blackzzzz.
So for your particular colour scheme, you could try red, orange or blue to go with the existing colours. A dark olive green might look good too but bright green could look a bit much with the pinky purple.