Give out an award to the student with the most classical style. Give this to the child who works in a careful and traditional manner. Perhaps the child enjoys painting still life or portraits. You can even name the award after a classic or traditional artist like Michelangelo or Degas. The award itself could be a paintbrush with the award name and child's name wrapped around the handle.
Award the child with the most unique style of art. Perhaps the child enjoys finger painting or abstract art, or something entirely new. This can help the child to realize that all types of art are important, and encourage her to continue in developing her personal style. You can name the award after a unique artist like Pablo Picasso or Vincent Van Gogh. The actual award can be in the form of an abstract work, printed out with the child's name and award name over the top of the piece.
Acknowledge the child with the most illustrative style of art. This can go to the child whose work tells a story, either in a literal or non literal sense. Maybe his painting depicts a scene as a story book would, or maybe there are a lot of interesting points to his piece that allow him to tell a story in a unique way. Name the award after a well-known illustrator such as Norman Rockwell. The award itself could be in book form. You can write the name of the award along with the child's name on the cover of a paper mache book.
Award the child who uses color to her advantage in her work. Perhaps she is quite good at using just a few colors together, or perhaps she uses many to create vibrant pieces. Name the award after an artist such as Andy Warhol, who favored color in his work, then print it on the back of a large color wheel. This will provide reference for the child's future use of color, and encourage her to explore her style even more.