User defined Function coloring in Mathematica

Question

Is there a trick to assign a specific color to "user-defined" function such as "function" below :

function[x_]:=x^3

Thanks to Mr.Wizard we are able to color all user defined symbols ( Syntax Coloring In Mathematica)

Would there be a way to refine the solution to have different colors for Functions symbols, Variables symbols & Options symbols ?

EDIT : Image for Simon