If the same dimension is being used on the color shelf in multiple sheets, the dimension members will retain the same colors throughout the workbook. To get around this, a duplicate of the dimension can be made (right click on it in the data box and select Duplicate), place it on the color shelf and assign it new colors.
In terms of colors for the pie chart, if there are not enough colors, a custom color palette can be created and imported into Tableau. The following Knowledge Base article provides further information on how to do this:
Hope this helps!
Tableau chooses colors based on whether the pill on the Color Shelf is continuous (green) or discrete (blue). Continuous pills get a quantitative series (the color bar on the Legend), Discrete pills get a categorical color set. You can click on the upper-right part of the Color legend and choose Edit Colors... to change the colors. Here's a link to the online help:
Thank you Tracy and Jonathan! Appreciate the help!!
Woops, answered the same question at the same time!