Here are some Stata code snippets for plotting multiple series. An example using the auto dataset that comes with Stata:
sysuse auto
twoway (scatter price weight if foreign == 1, mcolor(`f0')) (scatter price weight if foreign == 0, mcolor(`f1')),legend(lab(1 "Foreign") lab(2 "Domestic"))
The resulting graph shows domestic cars in the late 70s tend to be heavier for various price points.
Reference: st: RE: –twoway scatter- different colors for different observations [Statalist: The Stata Listserver], Stata Learning Module Graphics: Combining Twoway Scatterplots [UCLA Academic Technology Services]