If you have an itinerary in GPX format (with routes and route points) you can create a printable PDF map on Inkatlas. Smaller maps (6 pages or fewer) are free.
Full disclosure: this is my project.
Although not technically an online tool, ITN Converter allows you create precise itineraries following roads traced on top of maps from Google Maps. With ITN converter you can create journeys and way-points to be uploaded in satellite navigation systems, as well as exportable Google Maps journeys. You can do all of this via the Editor feature:
I don’t remember if you can customise line colours and such, and can’t test this feature since the Editor crashes when run from Wine on Linux. Try it out and let us know.
Credit:stackoverflow.com‘