py_trees.display
You can obtain an ascii/unicode art representation of the tree on stdout via py_trees.display.ascii_tree or py_trees.display.unicode_tree:
py_trees.display.ascii_tree
Similarly, py_trees.display.xhtml_tree generates a static or runtime representation of the tree as an embeddeble XHTML snippet.
API
A static representation of the tree as a dot graph is obtained via py_trees.display.dot_tree. Should you wish to render the dot graph to dot/png/svg images, make use of py_trees.display.render_dot_tree. Note that the dot graph representation does not generate runtime information for the tree (visited paths, status, ...).
Command Line Utility
You can also render any exposed method in your python packages that creates a tree and returns the root of the tree from the command line using the py-trees-render program. This is extremely useful when either designing your trees or auto-rendering dot graphs for documentation on CI.
Blackboxes and Visibility Levels
There is also an experimental feature that allows you to flag behaviours as blackboxes with multiple levels of granularity. This is purely for the purposes of showing different levels of detail in rendered dot graphs. A fullly rendered dot graph with hundreds of behaviours is not of much use when wanting to visualise the big picture.
The py-trees-demo-dot-graphs-program program serves as a self-contained example of this feature.