Preheat oven to 350° F.
Combine cake mix, grapefruit juice, oil, eggs and vanilla in a large mixing bowl. Beat with electric mixer on low speed for 1 minute until blended; beat 2 more minutes at medium-high speed. Beat in red food coloring until well blended.
Pour into greased and floured 12-cup Bundt pan.
Bake 45 to 50 minutes or until wooden pick inserted into center comes out clean. Cool in the pan on a wire rack 20 minutes; invert onto wire rack and cool for additional 30 minutes. Dust with powdered sugar before serving.
Servings: 12