The chart represents all Groups in the EP by color. Name and Members pop up when your mouse cursor is over any of them.
By clicking on a Group, all its Members will be displayed in a grid in alphabetical order.
You can get an overview of the Group based on Twitter metrics by selecting one of the available metrics in the unrollable list above the grid.
This column will contain the Tweet Search Box which allows you to scrutinize all tweets of the Group issued during the present mandate. After a filtering is applied, MEPs matching your filter will display in color and the rest will be grayed.
At this point you could read all tweets matching your filtering, just click on the MEP who issued them.
Select a Group and have fun.
All figures correct as at May 21st, 2019. 3,592,400 tweets and counting!