Needs["Graphics`ArgColors`"] ;
f = y;
e = 10;
g = -e (x^2 - 1) y - x;
Plot3D[{Abs[(f + g I)], ArgColor[f  +  g  I]}, {x, -2.1, 
        2.1}, {y, -11, 11}, ImageSize -> {400, 300}]