There are many ways that you can use art in your magic. The whole practicing of casting is an art. Here is a list of a few ways I like to use art in my magic workings.
I like making my own supplies. In order to use the things around me, I often make my own supplies. I make candles, and add a personal touch through the scent, color, and intention that I pour into them. You can also paint on symbols that relate to what you wish to do with the candle, or write words on them.
I make my own incense, using pine tar, dried ground herbs and twigs. You can make a mortar and pestle with clay, fire it, paint it, and put a glaze on it. You can make your own runes, tarot cards with your own designs. Sigils are a form of artwork.
You can make your own talismans with welding metal, molding clay, carving wood (or stone) and charging it. You can wrap crystals with wire in a decorative way while focusing on boosting the properties you want the most.
You can write your own spell (which itself would be a form of art) decorate it by writing in script, or in a color that goes with the intent of the spell. There are so many ways you can use art in your magic. Just use your imagination :)