The diagram below is a pretty good one:
Will the process be troublesome? Especially in the middle part, where to find such a graphic or freehand freeform curve?
If you are still using Excel2003, then I can only say that you draw slowly, it may take two days to draw out ... And for the Excel2010 version, as long as the following steps can be painted well.
First step: Insert your SmartArt
Step Two: Select the SmartArt graphic to choose on your own request
Step three: Enter the corresponding text in the box to the left of the following figure.
If the three is too few, continue to add:
To change the color applied style when you are not satisfied with its appearance color:
Until I'm satisfied.
There are a lot of shapes available to help you quickly create beautiful loops/hierarchies/graphs:
Hint: The SmartArt feature is also available in Word and PPT.