Conditional formatting would work. If the range of cells to affect were A2:A50...

1) Select A2:A50
2) Open Conditional Formatting and apply these settings:

Condition1: Formula Is: =LEFT(A2,1)="."
Format... Pattern... select a color


The trick is to highlight the range of cells and then enter the formula based on the current primary cell in the range selected, usually the first cell.