Add line plot with points. See the data arrangement trick to creat a gap in three different group coulmn.
We can format to remove lines in table if you think it makes the plot crouded.
If there are not alot of points, you can change data point colors, shapes etc so that they represent group they belong to. You can remove the data points and plot just lines connecting the points or not removing lines in first place (thus there will be both points and lines connecting points). Of course we can add more than one series by simply adding data series to plots.