However, I failed to suggest the obvious and most simple solution for not only changing all the gridlines in a worksheet to one color, but also setting them to many different colors. Thankfully, one alert reader called it to my attention. Michael A. Berson, CPA, CFO of Sidney Fetner Associates, New York, says you can produce variously colored gridlines (see screenshot below) within one worksheet by using the Format Cells command.
To do that, highlight the cell or cells to which you wish to add color. Right-click in that highlighted space, left-click on Format Cells and click on the Border tab. Select your color from the drop-down menu and then either choose the type of border from the array of choices or click on any of the corner symbols or the word Text in the center box. When you’re satisfied with the color and arrangement, click on OK .