There are a few ways to add sparkle to your coloring pages:
1. Color with sparkle type coloring utensils.
Many companies now offer glitter and metalic type pens/pencils/markers.
2. Color with regular pens/pencils/markers, then put
a sparkle wash over the parts of the pictures you want to 'pop'!
"Wink of Stella" has many glitter colors to play with.
3. After your page is colored, add some sparkly sticker bling.
My personal favorite brand is Dazzles from Paper Wishes.