I think legends are not supported by this node. (Probably it shows them if there is color information in the rows, not sure. I think it might also show three dots with different sizes for the "numorder" in your case.)
It seems this node do not support non-numeric columns as axis values, so having other values there is not possible (have you succeed to set them?).
I would recommend the Scatterplot node instead if it suits your needs better, though as I remember it do not support legends either.
I willl chip in here really quickly. The legend option does work, but only if you have a color manager upstream of the plot which is used to generate legend information. See the attached screenshots for the workflow and resulting plot.