How can I plot results from a particle filter in a weighted graphic?

I'm writing a particle filter and I would plot a graphic o my particle with their weights like in the picture below, I don't know ho to do that, I'm growing mad.

Basically I have k vector of Ns particles (with k = time sample), I have also k corresponding weights vectors with Ns elements, I would represent every particle with its weight (color intensity) for every k. I think that in the picture (not my picture obviously) the axis names are inverted.

At the moment I'm plotting the mean of the particles for each vector and I'm comparing it with the real state Xk but I would have a more complete vision of my particles.

Any help would be appreciated, sorry for my english.