I've been making some maps for a saga recently and I thought some people might find these ones mapping out the Mercere and Hermes portal links useful.
The first map is conservative and just goes on portals positively mentioned in published books (though as the extent of the portal networks are not really fixed in 5e YSMV):
The second map is more speculative and tries to guess where the redcaps might have a portal to have links to each tribunal, but these extra portals are entirely non-canon:
There are also annotated versions that explain the reasons for each link (or reference the book if canon) here: https://lexhermetica.wordpress.com/2021/01/09/maps-of-the-order-of-hermes-portal-network/
If you notice any mistakes or anything I've missed please let me know.
edit: Here's another version colour coded to show which edition each portal is mentioned in, thanks to @loke for the suggestion.