Sadly Matlab didn't enabled color-coded vectors in their ever so neat function quiver
Therefore there are endless detours open in Matlab, like the one I found for plotting what I think of:
"all vectors have the same size based on the optimum value for the grid provided"
Given that I don't understand the function itself I can't work out how . My best try is:
[x,y] = meshgrid(-2:0.2:2);
xr = -y;
yr = x;
What's looking pretty pretty (I mean, look at that clean arrows), but monochrome.