As mentioned in comments by @KanwarG the solution is to install Graphvis from as a proper package and not using the python package found using pip.
If using a mac then a solution is to used Homebrew. If you do not have Homebrew then follow these instructions to install it. Then it is easy to install Graphviz using the following command.
brew install graphviz
If you are using ubuntu Debian the following command is likely to work.
apt-get install graphviz
Hope this helps other people trying to find a solution.