Awhile back I shared a trick for quickly turning boring report numbers into colorized heat maps. Accenting data is something I find myself doing frequently in Excel. Although it offers many options for doing that (fonts, borders, fills, etc.), color is my preferred highlighting method.
Sometimes the default colors aren't enough or aren't appropriate for the task. Particularly when designing reports for printing, I prefer a broader range of lighter pastels; many of the default colors are just too strong.
Of course, Excel will let you assign custom colors to just about any element, and you can pick from over 16 million colors. The catch is that you'll have to fuss with the custom color selector, perhaps repeatedly, which can be time consuming.
Of course there's an easier way. Select the Page Layout tab from the Office Ribbon. Near the left end of the controls, pull down the Colors menu, and choose from a number of prefabricated alternate palettes. Any of these options will replace Office's default colors with a new set.
For my purposes (more pastels, for better printing), I find the color sets named Adjacency, Black Tie or Foundry are particularly handy. You can also achieve a new color set by choosing an entirely different Theme, but doing that will also change all your fonts and other display characteristics.