To get the colors from the point cloud onto the polygonizer mesh, you need to do something like this:

1. On the polygonizer mesh, create an ICE Tree.
2. Use Get Closest Location to get a location on the point cloud, get the color from that location.
3. Store that color somewhere (eg in an attribute on the polygonizer mesh, or in a vertex color map).

Here I’m storing the colors in a CAV:

And here I’m sticking the colors in a per-point Color attribute: