To create a Nyquist Plot just enter the Transfer Function using the Root Locus Made Easy app at https://www.tinspireapps.com/?a=RLME to get Nyquist Plots as shown below.
Example1: The transfer function
yields the Nyquist Plot:
Example2:
This is part of the Root Locus Made Easy for the Ti-Nspire at https://www.tinspireapps.com/?a=RLME , so you can create Nyquist and Root Locus plots using the same APP.