The Elements of Graphing Data by William S. Cleveland has come highly recommended even though this is the 2nd edition of a rather old book. The contents focus on how and why we use visual data representations, which should also help you with the language that you use to describe data in both your presentations and writings.Another of Cleveland’s books comes highly recommended is Visualizing Data. This is a newer release (1993) and seems to focus a little more on the types of data visualizations and their usefulness. Either of these books seem like they would be helpful to anyone who needs to work with and present data in the most eloquent way possible. Let me know if you have any other suggestions.