Screen Gems, which had the Universal monster catalog ready to sell to TV stations across America, sent out a promotional book to TV program directors in October, 1957. The rectangular 11" x 14" publication was plastic-comb bound. The top part of the cover shows a man's frightened upper face peering through his fingers. The bottom part of the cover shows John Carradine as Dracula, Bela Lugosi as the Frankenstein Monster, Lon Chaney Jr. as the Wolf Man, Eric the Ape from MURDERS IN THE RUE MORGUE and Noble Johnson as Janos, from the same film. In between is the now legendary name for the film package being presented: SHOCK!
We currently do not know who the cover artist was, nor do we know the names of the person or persons who thought up the campaign, including the SHOCK! title. Perhaps one day an investigation in the archives of Columbia Pictures' Screen Gems, if such archives exist, will give us the answers.
Regarding the artist, I would consider the possibility that two artists worked on the cover, one for the top work and the other for the monster gallery bottom, which is a tad more primitive than what's above it.