viewport color randomizer.py

import bpy
import math
width = max(1,math.ceil(len(bpy.data.materials)**(1/3) ))

for i in range(width):
    for j in range(width):
        for n in range(width):
            try:
                bpy.data.materials[i*width*width+j*width+n].diffuse_color = (i/width,j/width,n/width,1)
            except:
                pass