How to change meterial property in Unity legacy animation?

Hello.

I want to change the material characteristics such as color in Unity Legacy Animation.

However, the option could not be found in the animation window.

The reference geometry is as follows.
Parent (Animation)
-> 1 (Skinned Mesh Render) => Materials have more than one.

In the example I was practicing, it looks like the picture below, so I would appreciate it if you could tell me how to solve it.