In a large bowl, beat sugar and butter until crumbly; stir in the eggs and salt. Combine flour and baking soda; stir into sugar mixture until combined. Drain cherries, reserving 1/2 cup juice; set juice aside. Gently stir cherries and walnuts into sugar mixture.
Pour into a greased 13x9-in. baking dish. Bake at 350° for 40-45 minutes or until a toothpick inserted in the center comes out clean. Cool completely on a wire rack.
For topping, in a small bowl, beat cream and confectioners' sugar until soft peaks form. Spread over cake; refrigerate for 2 hours.
In a small saucepan, combine sugar and cornstarch. Stir in reserved cherry juice until smooth. Stir in food coloring if desired. Bring to a boil over medium heat; cook and stir for 2 minutes or until thickened. Cool. Just before serving, drizzle over whipped cream. Refrigerate leftovers.