Hi there,
I believe that you'll still need to optimize the model.
Please consider that if your model has been imported from a 3rd party app/host software, it will be loaded into C4D as a triangulated mesh, which is normal.
Once in C4D, you need to optimize the model (cleaning the model a bit); you can use the "Optimize" command and then run the "Untriangulate" command and see if the resulting mesh is what you're looking for.
You can't magically expect to solve the issues that come with an imported model made in another software.
I think I understand the result you're looking for, but still, I'll suggest first cleaning/optimizing your model, then using a shader or maybe using the suggestion provided by Beanzvision will take you to the desired result.
Cheers ;)