How to plot constellation diagram for 8 - PSK modulation ?

I wants to plot the constellation diagram for 8 - PSK modulation. The modulation is at the baseband data. I have three signals for the same which modulated the input data stream into 8 - PSK modulation. These are I, Q & Signal waveforms. I have captured these data on Oscilloscope. But not sure how will I use these captured data to plot the constellation diagram. In oscilloscopes, there is XY mode but will be only useful to plot QPSK modulation constellation.

Can anyone help on how I can use these captured ".csv" data further in MATLAB to plot the Constellation Diagram ?

My license number is : 416213.

Regards,

Nikhil Mitaliya