Why? a) To give me a visual aide memoire of the week notes. b) To give others a more visual entry point in to my digital garden.
I started with very visual and very time consuming slides made in LibreOffice Impress. See: Captain's Log. I still really like those, but I couldn't find the time to make them each week.
Then I fiddled a little bit with PlantUML. Marginally less work than building from scratch, but still time-consuming, having to write the PlantUML markup. Good fun, but if I'm spending actual real time on it, I'd rather the creation process itself be visual and free-flowing.
Next up I've been trying graphs built automatically with org-roam-graph. I put the links to the daily journals in the weeknotes file, generate the graph, have a peruse of it and write my weeknotes from then. Then remove the journal links and just generate the graph from the weeknote links. It works as a nice easy-to-generate visual aide memoire for me, though sadly it's not really very visually compelling for anyone else.