Legend for graphs with marker symbol invisible

Hello,

I am graphing a twoway dot, with two variables.

I can´t seem to find a way to add a legend (it will display with no color) to the graph when the marker symbol is invisible and the marker label is the value of the variables, since there is no actual marker symbol to display, but the marker labels do have different colors for each variable.

I would appreciate some help with this,
Thank you