I know a lot of people don't like multicolored manes on original ponies (especially if it's more than 3) but I think it looks good and makes some ponies look better but only if you use similar colors like red orange and gold or colors that go together well like light blue light pink and light orange. So you can pick colors close together on the color wheel or colors that share an attribute like pastel colors, dark colors, light colors, earthy colors, faded colors...
Like for my pony I used brown, gray purple and gray green, it looks good because all the colors are grayish and neutral
see (also note how I'm standing on the moon) or this pony
I would post more buz I can't find any.
Also don't go overboard with random patterns like this thing here.