Why the initial color of model disappear after adding light

I just use vertex array, color array to draw my data, and the each color of vertex as well. Before I opening the light, the model’s color is as the same as I set, however, the color change to the light’s one after I using the lighting and material setup.
I want to use different color to discrible my mesh. What can I do to get my model’s former color back?

To use per vertex colors with lighting you need to enable the color material using the glColorMaterial function.