I think Speedskater is talking about the "Power Distribution" chart, not the Peak values or summary info in the Ranges panel.
If that's the case, what you can do is:
1) Select the portion of the graph that represents the race, without warm-up/cool-down.
2) Click Copy in the toolbar (or press Ctrl+C)
3) Click New Workout (or Ctrl+N)
4) Switch to the Graph view of the new workout
5) Click Paste (or Ctrl+V)
Voilà! You should now have a workout file that only represents the race. Now you can go to the Journal tab to create any graph you desire!
Hope this helps!