I'd think using plots to test the assumptions of multiple linear regression requires some experience anyway, but in this case all my independent variables, and my dependent variable, are 5-level Likert rather than continuous variables.
I understand applying non-ordinal regression to this kind of data is somewhat controversial, but is often done.
The plot consists of 5 linear arrays of points at 45 degrees. Is that interpretable at all?
If not, what should be substituted?