Activity Graph:
Choose an activity from the Diary. Along with all statistics and data, a graph will show the Speed or Hearth Rate point. Click on a point of the graph to move the related point on the map and see details.

General Stats and Graph:
Click on 'Statistics'. You will be able to get a graph for Max speed, Avg speed, Distance, Duration, grouped  Daily, Weekly, or Monthly. Choose the period to analyze and if you want you can export it.

Please note: General Stats and Graphs are available only if you subscribed to Waterspeed Pro (see the related article for details). Activity Graph is available for every user.