When a Column chart in PowerPoint contains only one Data Series and several Categories, then, by default the individual chart columns may use the same fill color. If your chart uses the same colored series in all of the categories, it can make your chart look dull (see Figure 2 later on this page) — it also does not provide a proper way for your audience to compare elements within the individual series.
Learn how to show different categories in different colors within a chart.

