From what I understand is that you have complex valued Voltages(Volt) and Currents(Cur). To get the impedance value for a particular value of voltage and current, the following relations will hold.
R = real(Volt/Cur);
X = imag(Volt/Cur);
Now to get the impedance diagram you just need to plot the data obtained above in appropriate axes.
Let me know if this is what you intend to do.
