Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, mix together butter and sugar until fluffy. Add in egg and vanilla extract and mix until smooth.
Add in the flour mixture, and mix until it is fully combined. Divide the cookie dough into two bowls, and mix one with purple food coloring and one with orange. In a shallow dish, whisk sugar and cinnamon together.
Take a small amount of each cookie dough and roll into balls. Roll in the cinnamon sugar mixture and place onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.
