I'm not really convinced S-exprs are particularly good examples of representing trees and graphs to humans while expecting them to be as easily readable and writable as the graphical forms.
You lose spatial intuition with this representation. You could make up for it on small trees somewhat with indentation and vertical spacing, but you'd lose it again for larger trees and graphs. We don't pictorially represent our trees like this [1], for instance, which is roughly how the S-exprs visually appear.
When I author graphs in LaTeX, it is often easier to run through a compilation cycle to see what the result looks like and which edits are needed, rather than mentally reasoning about the edges by looking at the code.
You lose spatial intuition with this representation. You could make up for it on small trees somewhat with indentation and vertical spacing, but you'd lose it again for larger trees and graphs. We don't pictorially represent our trees like this [1], for instance, which is roughly how the S-exprs visually appear.
When I author graphs in LaTeX, it is often easier to run through a compilation cycle to see what the result looks like and which edits are needed, rather than mentally reasoning about the edges by looking at the code.
[1] http://i.imgur.com/43Dc8YB.png