I can share my own experience. To make the diagrams with colored edges we use different line styles (dashed, dotted, bold, normal). We post the color version
in the arxiv. When people print it b/w, the style of the lines still can be distinguished. Of course we explain in the text writing something like this: red line (dashed)... .Some journals publish color pictures in online versions.
Few journals publish color pictures on paper.

For other types of diagram you can fill the regions with different filling style,
AND use color. The regions will differ both in color and in b/w print.