Makin's Clay is one of the air-dry clays that is available in colors. However, if you want to use Creative Paperclay for this project or another brand that is only available in white, you can pre-tint the clay with acrylic paints or a little bit of cake colorant paste, like that made by Wilton.
Have you ever made flowers with clay? Many brands of air-dry clay can be made into very thin, translucent petals that are also strong. "Craft Ideas for All" has a nice little tutorial for creating roses and cherry blossoms to make the pretty arrangment shown here. Other posts on their blog indicate that they use both Delight clay and Deco clay for their flowers.
Tip: This tutorial tints the air-dry clay with acrylic paints. A less messy method is to use paste cake colorants like those made by Wilton . Colorant sets are available in soft pastel, flower colors.
Go to http://pottery.about.com/od/surfacetreatments/ss/impressed.htm for some ideas for creating texture in your clay using everyday objects such as rubber stamps, roulettes and coggles, pine cones, branches, twigs, stems, barrettes, balls of twine, bottoms of bottles, woven wicker and grass baskets.