Series.InvertColorIndex (Excel)
Returns or sets the fill color for negative data points in a series.
The InvertColorIndex property enables you to set the fill color for negative data points as a color index value from 0 to 56. For more information about color index values, see Adding color to Excel 2007 worksheets by using the ColorIndex property. Instead of using the InvertColorIndex property, you can use the InvertColor property, which enables you to set the color as a specific numeric, hexadecimal, octal, or RGB color value. For the InvertColorIndex property to have an effect, the InvertIfNegative property of the Series object must also be set to True.
ActiveSheet.ChartObjects("Chart 2").Activate
ActiveChart.SeriesCollection(1).InvertIfNegative = True
ActiveChart.SeriesCollection(1).InvertColorIndex = 7