Preheat the oven to 350 degrees F (175 degrees C). Grease and flour a 12x8-inch fluted tube pan (such as Bundt®).
Sift flour, baking soda, salt, and cinnamon together in a large bowl and set aside.
Cut 3/4 cup raspberries in half and leave remaining 1/4 cup whole. Set aside.
Combine sugar and oil in a large bowl; mix well. Blend sour cream, pumpkin, and vanilla extract into the mixture using an electric mixer. Beat in eggs one at a time. Beat in flour mixture gradually until combined. Stir in walnuts. Fold in halved raspberries. Spread batter into the prepared pan.
Bake in the preheated oven until a toothpick inserted into the center of the cake comes out clean, 55 to 60 minutes. Remove from the oven and let cool completely, about 30 minutes.
Beat confectioners' sugar, cream cheese, red food coloring, and yellow food coloring together in a large bowl until smooth. Fold in whipped topping. Frost cooled cake and decorate with reserved whole raspberries.