If the above article piques your curiosity about Kaprekar's constant (6174), I wrote a blog post[1] last month that goes into some depth and has some nice visualizations.
I was thinking about generating a graph of connected nodes like the one you did. But TBH, i really like the ones on Wikipedia[1], and didn't really feel like making something of equal quality hehe.
[1]: https://www.oranlooney.com/post/kaprekar/