Click on the link on the top right of the page to see. C/P'd for convenience:

This graph shows the sentiment of tweets about Bernie, Hillary and Trump over time. The location of the line along the y-axis shows the average positivity (or negativity) of tweets about each candidate. The width of each line shows the volume of tweets (thicker line = more tweets). Sentiment analysis is done via Indico’s API, which is awesome. Tweets are streamed via Twitter’s Streaming API, because obviously. Built by Will Tachau

I'm curious how accurate the sentiment analysis is when dealing with sarcasm, which I suspect is especially popular in tweets about politicians.