Preheat the oven to 180 degrees C. Grease and flour a 20x30cm baking dish.
Stir together the sugar and vegetable oil in a large bowl until smooth. Beat in the eggs one at a time then stir in the vanilla and sweet potatoes.
Bake for 35 minutes in the preheated oven or until a knife inserted into the centre of the cake comes out clean. Cool completely before icing or serving.
Combine the flour, baking powder, bicarb soda, salt and cinnamon in a separate bowl; stir into the batter 1 cup at a time alternating with the beer just until everything comes together. Spread the batter evenly in the prepared pan.