recently i've been through this problem and to try to solve i searched in colab documents and foruns and i dont found no way to plot on Colab. But, i discovered the Jupyter Lab, that is similar to Colab can handle with markdown and it's easy to use, beside it runs on your own Computer, which can be bad in some ways.
Here is an example image of Jupyter Lab with Plotly:
Plotly in Jupyter

And i found a comparative of Colab and Jupyter:
https://www.geeksforgeeks.org/blogs/google-collab-vs-jupyter-notebook/