The django-extensions contain a great command to visualize the model hierarchy of a Django project:
$ apt-get install graphviz $ pip install pygraphviz $ pip install django-extensions
# In your Django settings INSTALLED_APPS = [ "django_extensions", ]
Then you can get a zoomable vector graphic from all models of one app like so:
$ python manage.py graph_models my_app -o my_app_models.svg
The result may look like below, but make sure to explore the command options, it can be customized alot especially when you want to limit which models to draw.