laying out a large graph with graphviz

Try this:

sfdp -x -Goverlap=scale -Tpng data.dot > data.png

The -Goverlap preserves the layout but uniformly scales things up until there are no more node overlaps. I was able to get a ~77MB PNG that looks like this when you zoom out.

you could still use the neato but modify the .dot file putting: [splines=true overlap=false]

And your file should look like this:

digraph luffarschack {
    graph [splines=true overlap=false];
    node [shape=none]; 
        ...here your nodes;
        ...here your edges;
}

It should work if you just put in the second line "graph [splines=true overlap=false]" and everything else remains the same.

In addition to other answers, you may use other tools like Gephi.

Gephi is the leading visualization and exploration software for all kinds of graphs and networks. Gephi is open-source and free.

Runs on Windows, Mac OS X and Linux.