Here it is:
Show[DensityPlot[Sin[3 Arg[(x + I y)^3 - 1]], {x, -2, 2}, {y, -2, 2},
ColorFunction -> "Rainbow", Exclusions -> None, PlotPoints -> 61],
ListPlot[Table[{Re[E^(I*2 \[Pi]*n/12)], Im[E^(I*2 \[Pi]*n/12)]}, {n,
0, 20}], AspectRatio -> Automatic,
PlotStyle -> {{ Black, PointSize[.02]}}],
Table[
Graphics [{Thick, Dashed, Black,
Line[{{Re[E^(I*2 \[Pi]*n/12)], Im[E^(I*2 \[Pi]*n/12)]},
{Re[E^(I*2 \[Pi]*(n + 1)/12)],
Im[E^(I*2 \[Pi]*(n + 1)/12)]}}]}], {n, 0, 20}]]
