You need to use the ShapeDiverDisplayGeometry component to assign ShapeDiverSimpleMaterials or ShapeDiverMaterials to geometry. The component takes two inputs: the geometry to display, and the material definition that is returned by one of the two material components mentioned above.
If you want to apply materials to different geometry, you don't need to create a ShapeDiverDisplayGeometry component for each geometry, instead, you can input a data tree in the Geometry input and a list of materials in the Material input. Unlike the traditional way of matching tree branches, we match each branch with an item in the materials list.
The reason why we don't use data trees in both inputs is because you can apply one material to various geometries but you can not apply various materials to one geometry.