You can use RGB color codes, with them you can use really many colors.
It can simply be donw like that:
Code
[color=RGB(255,0,0)]red[/color]
redThe first number is red, the 2nd green, and the 3rd blue.
The numbers go from 0 to 255, you may use any combination.
Code
[color=RGB(255,0,0)]1[/color][color=RGB(0,150,22)]2[/color][color=RGB(155,0,105)]3[/color][color=RGB(0,0,0)]4[/color][color=RGB(0,0,255)]5[/color]
12345You can also use hexadecimal values, but RGB(red,green,blue) should be easier if you are not used to hexadecimal numbers.