Grapher has the ability to assign different fill properties such as fill color based on whether the bar is above or below a user-defined base value. This applies to the following bar chart types: 2D Vertical/Horizontal, 3D Vertical/Horizontal, and Category Vertical/Horizontal.

To color positive and negative bars different colors:

1. Create the bar chart of your choice using the Home | New Graph | Basic | <bar chart type> select the data file and click Open. 
2. In the Object Manager, select the bar chart layer.
3. In the Property Manager, on the Plot page, set the Base value in the Plot Options section to 0.
4. On the Fill page, check the box next to Different fill if bars<base. 
   
5. Expand each Fill Properties section and select the desired Foreground color.

Updated July 2019