Hi TAK,
Please have a look to the scene file.
As it is a straight spline in your scene, you can just use a “Plain Effector” to introduce a change of the color—from black to white. This change is based on the fall off.
THe color of each clone is then used in the MoGraph Color Shader. This allows to use the “Clone Color” in a Layermask function inside the Layer Shader. In this way the change of “color” creates the change. (It is only visible after rendering!)
Please note, the Shader Effector is not usable for any direct texture or Shader work of Clones. It takes for each clone a SINGLE value out of a texture and provides this SINGLE value (e.g., RGB) for the PSR parameter inside of the Effector or for further use in e.g., the MG Color Shader. Textures as in Materials are not provided as they are for any texture work.
All the best
Sassi