With the entire cast, so much of this chart would be words, instead of graphical representation, which would almost defeat the purpose of the chart.
Are you sure about that? Maybe we have different ideas of how Venn Diagrams work. As I see it, the names shouldn't repeat themselves, as they do in your example. You wouldn't write "Character A+Character X", "Character A+Character Y", "Character A+Character Z" and so forth - rather, Characters A, X, Y and Z would be inside the same circle - but X, Y and Z would be in circles pertaining to each other that accurately reflected their relationship to each other. You see how this would get confusing?
These circles would have to be color-coded to accurately reflect their relationship. Character A would also be in a few overlapping circles - with
mutual friends, enemies and so on - as would X, Y and Z. So the text shouldn't be heavy at all - just one instance of each name. You just have to arrange the overlapping circles and the sets within them correctly. That would include not having two separate instances of the same name (such as "Marisa+Sanori" - guessing you meant "Satori" there - and "Koishi+ Satori").
These permutations are why I say things would get confusing to map out. If you just tack repeating names together in the same circles, yeah, that gets text-heavy and very boring, but I'm pretty sure that'd be cutting some Venn Diagram corners, and would indeed be sloppy to look at.
Edited for clarity, hopefully.