For a feasibility problem (no objective function) CPLEX will terminate when it finds a feasible solution. There is no way to obtain all extreme points.
What you could try:
- set an objective function
- solve and store solution
- modify the objective function to find a different solution (which has to be done randomly, if you want random solutions)
You would have to use some API to code the logic. This idea is described in more detail here: http://orinanobworld.blogspot.de/2013/02/finding-multiple-extreme-rays.html
But, this is way to complicated for your problem. I'd simply do the following:
- set z randomly
- calculate x + y = z + 41.3
- select a random r between 0 and 1
- x = (x+y) * r
- y = (x+y) * (1-r)