Points not yellow in ggplot2

I am trying to draw a plot using following code but the points are not yellow.

ggplot(data=mpg) + geom_point(mapping = aes(x=displ, y=hwy, color="yellow"))

Output:

You can move the axis mappings to ggplot() from geom_point() and do this:

ggplot(data=mpg, mapping=aes(x=displ, y=hwy)) + geom_point(color=“yellow”)