[SpinyNorman]

I don't now about radically different.. after all a graph is just a bunch of nodes, edges and associated attributes. There are standard alternatives to the DOT/GV graph description language though, such as GraphML (XML based) and GML (others too, but these seem to be most supported).

For graph layout, tools worth looking at include OGDF (an open source C++ library), the commercial yFiles Java library with free yEd editor/layout tool (includes support for GraphML attributes), and Gephi (an open source Java-based graph layout/visualization tool).

If your graph represents some type of directed dataflow, then maybe Google's Tensorboard graph visualizer (intended primarily for neural nets) is of interest - it's open source and very slick (esp. wrt subgraph collapsing/expanding), but you'd be on your own in terms of importing a foreign graph format.