From http://www.mail-archive.com/ntg-context@ntg.nl/msg44867.html it appears that \setupinteraction affects the \setupurl command when no url is given. This was not  obvious from the documentation.

It seems that assigning different colours for internal (e.g., cross-references, table of contents, and indexes) vs. external links (e.g., web sites) is not possible without creating new macros that use the \color macro?

Kind regards.