In most cases there are too many jellies to deal with in only 20 moves, as many of them are located under two-layered icing. They are also on the sides of the board, which is awkwardly shaped, making them even harder to reach.
With five colours, special candies or combinations are not too hard to make, but even so, there are almost always two or three jellies you do not manage to reach by the end of the level.
Focus on creating special candy combinations at the top of the board. This will help you to clear the icing that is blocking the jelly squares at the bottom.
Special candies can be very beneficial in this level. If you are able to get a colour bomb, try to hold on to it and combine it with another special candy. This way it will clear a majority of the jelly and icing squares.