Using a CRP5 I get about 745 Kts TAS.
If all you want is general trends then at 40000 ft pressure altitude in the ISA, the relative density is about 1/4 so the TAS is about twice the CAS. (TAS = CAS / sqr root of 1/4)
If you are not interested in the numbers, but simply want the general effects, just draw four straight lines starting at a common point and fanning out as they move upwards from the bottom of a sheet of paper. Mark these lines from left to right, EAS, CAS, TAS and Mach.
To test the effect of climbing at constant CAS for example, rotate the sheet so that the CAS line is vertical. The EAS line will now slope to the left as it moves up the sheet. This indicates that EAS decreases with increasing altitude. The TAS and Mach lines slope to the right indicating that these values increase as altitude increases.
For a descent just look at how the lines slope as you move down the page. Sloping left means decreasing values and sloping right means increasing.
By rotating the sheet so that the appropriate line is vertical you can test the effects of climbing or descending with constant EAS, CAS, TAS or Mach.
You can also modify the lines to test the effects of inversions and isothermal layers.
For an inversion draw the four lines fanning out as before, but label them EAS, CAS Mach and TAS from left to right.
For an isothermal draw three lines fanning out from the bottom. Label the first line EAS, the second line CAS and the third line Mach and TAS.