Here's another option. ;)
I wrote a small Python program to solve Kepler's equation and create mathematically accurate orbit diagrams. My code produces its output in the SVG vector graphics format, so there's no pixelization when you zoom in, or print it. Unfortunately, this site doesn't support SVG files (although they can be inserted into posts on Stack Overflow), so here's a medium resolution PNG preview.
The actual SVG file is fairly small, and you can see the SVG code & the image it produces, courtesy of SageMathCell, by clicking this link. (The SVG data is actually encoded into the URL). Or you can view the image & its source on GitHub. You can also click the PNG version to see the SVG on GitHub.
Any modern Web browser can display SVG files, just put that code into a plain text file and save it with a
.html will probably work too. (And it's very easy to embed SVG into a HTML file).
This image & the SVG code is freely shareable & reusable under the conditions of the CC-BY-SA license linked at the foot of this page. That is, you can use it if you give me proper attribution, and where practical, link to this post.