Is it possible to change the default Black colour used for element edges in a shaded view of the mesh in ABAQUS?

Yes its possible to change the colour Black. Click on the Common Plot option icon (the first one first row and the one on the left to the left of the viewport).

In the dialog box which opens choose the Color & style tab. There will be 3 lines of colours. The second one controls the colour of the edges of the elements in the mesh. Click on this colour and from the colour palette which appears choose the colour and click on OK. Click on OK and this should change the appearance.
See the second figure for the one before the previous question, where the Black colour has been replaced with Red.