I had a similar question a while back when I was trying to format
pivot tables with VBA.
Excel shows the button face color in a cell in the header of a pivot
table when the pivot table is originally created. When you apply a
std. cell color to the header cells of the pivot table there seems to
be no way to restore the button face color for these cells other than
completely resetting the whole pivot table formatting by setting the
pivottable property .PreserveFormatting= false. I've spent some time
exploring the object model of the pivot table to see whether I can
find anything that defines this button face color for the header
cells, or that can be used directly to reset only the interior color
of these cells instead of resetting the format of the whole pivot
table. I couldn't find anything. Does someone know a better way???