Color is perhaps the most important aspect of figure style, and thus it deserves its own subsection. There are many great resources that discuss the principles of choosing colors in visualizations (for example, https://betterfigures.org/2015/06/23/picking-a-colour-scale-for-scientific-graphics/ and https://earthobservatory.nasa.gov/blogs/elegantfigures/2013/08/05/subtleties-of-color-part-1-of-6/). The official Matplotlib documentation also contains a good overview of color maps (http://matplotlib.org/users/colormaps.html).

Effective use of color adds sufficient contrast to make something stand out and draw your audience's attention. Colors can also evoke emotions; for example, red is often associated with important or passionate, while green is often associated with natural or stable. If you are trying to deliver a story from your plots, do try to use an appropriate color scheme. It's estimated that 8% of men and 0.5% of women suffer from red-green color blindness, so we need to pick colors with these individuals in mind as well.