Last year with Adding AWS Icons to PlantUML Sequence Diagrams I started making my diagrams look a bit better. However, the native sprite format looked somewhat washed out to me.
My investigations resulted in some Python coding and deeper understanding of the PlantUML syntax, which resulted in using PNG icons with full color fidelity. This was included in Release 13.0 and now I’m a maintainer on another open-source project.
Here is an example of what they look like: