"Utilities->Color" is a tool to set a color palette for the displayed 3dr file.
You need to edit a Color Palette File, which has the format:
index1 r1 g1 b1
index2 r2 g2 b2
index3 r3 g3 b3
index4 r4 g4 b4
......
Each index is a floating point number pointing to the pixel values in the data file. r, g, b are the RGB indices to define the color in RGB model.