Press and hold the Shift key, click on a blank area of the Storm and drag the cursor to select as many stickies as you like.
The selected sticky notes will have a blue outline.
A new menu will pop-up at the top of your screen showing you the number of stickies you selected and giving you different options.
Select the color in the Color Palette that you would like to change the stickies to.
Note: Locked stickies will not be able to be selected, you will need to unlock the stickies first.