https://www.npmjs.com/package/canvas is a server-side implementation of the canvas API backed by Cairo. It looks like you should install http://cairographics.org first.

If so, we should probably update the Graphoid documentation to reflect that

I think Graphoid does not have any documentation, we/i should write it. I dug up these notes, but not sure of relevancy any more

sudo apt-get install nodejs-legacy npm libcairo2-dev libjpeg-dev libgif-dev
cd /vagrant/mediawiki/extensions/Graph/nodejs
npm install vega
npm install nodemw
npm install async

on vagrant:
sudo apt-get install nodejs libcairo2-dev libjpeg-dev libgif-dev
npm install vega
npm install nodemw
npm install async