I also ran into this logical roadblock when dabbling with procedural generation. How to get nodes and edges from a procedural Voronoi map? The data is there but how to get to it to utilize it...

I think if I had continued I would tried layering it on top of another procedural map, for example terrain/elevation, to further further modify the elevation values or add terrain features to suit a particular biome, based strictly on the value returned by the Voronoi noise at each coordinate.

Another idea I had, if using the Voronoi noise pattern to define spaces like on a board/tactical game for example, would be to use some sort of flood fill algorithm on any given spot until the returned value changes. Then at least I would be able to get the top/bottom/left/right bounds of any cell area, and maybe use the center of that as a node position. Defining edges between nodes should be simple enough from there.

For a more accurate node position, you might be able to count and weigh the number of tiles/pixels in any particular cell and see how many fall in each quadrant relative from the "center". That might be just running the actual Voronoi noise algorithm backwards, I don't know. The formula should be out there.

No ideas on how to get vertices and their edges though, to draw borders between cells or implement something like a river between biomes...

Sorry if this doesn't help much, just thinking out loud. I didn't get very far in my experiments myself. I suspect you'll find more insight at /r/proceduralgeneration/ than on these forums, even if they aren't familiar with Construct. They would probably have more ideas and experience on how to use and apply the results by themselves even when the generation of the noise is obfuscated.