If you don’t need to embed the graphs in documents like PDF. I had high success using highcharts, chart.js o morris.js… there are a lot of libraries, but all of them works with json data.
You could implement a controller method returning data in json format or simply, do json_encode in a script tag after formatting the data. I usually grab all the required data from the db and put the transformation login in the view file, so I can transform my entities data to the json format used by the chart library I’m using.