with geom_star(), ggstar provides geoms for ggplot2 to create more easily discernible shapes:
ggplot(data=iris, aes(x=Sepal.Width,y=Sepal.Length)) +
geom_star(aes(starshape=Species, color=Species), size=1.5) +
scale_fill_manual(values=c("#E41A1C", "#377EB8", "#4DAF4A")) +
theme(legend.spacing.y = unit(0.02, "cm"))