https://wiki.project1999.com/Zone_Connection_World
In theory it would be possible to write an automated tool (it's a variant of a classic programming problem "the traveling salesman"), but I don't think anyone has done so yet ... so the maps I linked above are probably your best bet.
Oh, and if you did want to automate it, I'd be happy to help with the web bits (as a JS dev myself). We even have a JSON zone data file in the wiki (
https://wiki.project1999.com/MediaWiki:Zones.js) ... but it doesn't yet have the connections, so someone would need to parse them out of the HTML.