Hi Poamuri, you can not automate the graph and charts using selenium, but the values which are displayed on charts can validate as long as you read those from back end code level. Now a days every one using the third party plugins for creation or generation of charts.
Highcahrts is one of the popular one, But these charts are generated based on custom tags, so you have to create xpaths for these custom tags to read the values from high charts.
beyond to that still you can validate the graph colors and percentage of filling on piecharts, but this need to develop custom methods based on your needs and type of graphs
