[iso8859-1]

Does OSM also store information about lines? When I click a station in Google Maps, it sometimes shows colored lines.

[e4e5]

I just quickly looked at it, and bus stops seem to have a tag with the line, might be spotty though

[Symbiote]

Try https://www.openstreetmap.org/#map=15/51.5171/-0.1266&layers...

(There are several layers to choose from.)