I have GraphViz 2.32 installed in Windows 8 and have added C:\\Program Files (x86)\\Graphviz2.32\\bin to the System PATH variable. Still pydot is unable to find its executab
install Graphviz here and add its bin path solved my problem
https://graphviz.gitlab.io/_pages/Download/Download_windows.html
pip install Graphviz itself seems inadequate