CAESAR II will never behave like this. CAESAR II uses simple "3D Beam Elements", there is no real mesh like you would have in an FEA package. The colors shown in those plots are an interpolation between the two values assigned to the nodes. This is why there can sometimes be a disconnect between two elements - node 10 on the from end of one elment may only be stressed to 40% of the allowable, while node 10 on the 'to' end of the next element might be stressed to 120% of the allowable. You won't have that if you had a mesh with more complex elements.

You may be able to improve things by using more nodes, but that seems like a lot of work just to improve color shading.