How to create a colored point cloud from shapenet dataset?

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

I want to create colored point cloud from shapenet dataset and when I try use this simple code I do not get color information:

import open3d as o3d
import numpy as np

instance_file_path = "../39be4ef0dfa6833e49c9c494c2fb14ce/models/model_normalized.obj"
mesh_instance = o3d.io.read_triangle_mesh(instance_file_path, True)
pc_instance = mesh_instance.sample_points_uniformly(100)
pc_coordinates = np.asarray(pc_instance.points)
pc_colors = np.asarray(pc_instance.colors)

pc_colors are empty. I am also attaching the sample data. I am just starting to use open3d and would be very happy if someone could help.

[39be4ef0dfa6833e49c9c494c2fb14ce.zip](https://github.com/isl-org/Open3D/files/8040478/39be4ef0dfa6833e49c9c494c2fb14ce.zip)