The best command for creating graphs like these would be the Connect command.
For example, we just posted an example files for a Dendrogram Plots.
The file will create a plain plot.
You could also add color schemes to the lines.
This can also be plotted as nodes.
Note that DataGraph is not determining the nodes, just drawing the output. For example, we are looking at how you could use the DataGraph R package to read the output from an R clustering algorithm directly.
If you have a specific dataset we could work on an example file.
The Sankey diagrams with the width changing across the graph would be tricky in DataGraph but the connections from side-to-side are something you could represent.