`colorcet` has a swatch function in the plotting module that creates an image of the colormap. <img width="1048" alt="Screen Shot 2019-11-06 at 3 00 22 PM" src="https://user-images.githubusercontent.com/4806877/68333441-85f1aa00-00a6-11ea-99b0-d9ef9726c916.png"> I think that the colormaps should have a `_repr_html_` that does something similar.