The narrative is that the pope is seen screaming and yet we do not hear any voice which is symbolic of him being silenced by the shroud of falling colors from above. Bacon in his interviews says that he has nothing against the Popes but his paintings obviously detests them.
The painting Henry VI is about the same subject – Pope Innocent X but is actually a product of an overworked painting that the canvass almost clogged. In this work, this is thickly painted by oil on canvass and without the use of glaze such as the earlier work on the Pope.
Its narrative is similar as the Pope is screaming but is silenced by the dark colors. Curiously, this one is a bit different because he is caged in a transparent box suggesting that the man inside may have been suffocated that he had to scream.