The Saddlers, unbeaten in 12 and hoping to make the play-offs, avenged a 5-1 defeat at Coventry in November and were already two ahead when the Sky Blues lost Jordan Stewart to a red card.
In a lively opening, Craig Westcarr shot across the face of the Coventry goal on seven minutes and Sky Blues keeper Joe Murphy saved well from Andy Taylor, before William Edjenguele headed just wide for the visitors.
But Walsall took the lead they deserved in the 33rd minute, James Chambers and Sam Mantom combining to release Paterson who nipped round a defender and drilled home a low, right-foot shot for his 12th goal of the season.
Walsall made it two in the 53rd minute when James Baxendale was tripped by Aaron Martin and Westcarr hammered in the penalty.
Stewart was sent off for a second yellow card in the 65th minute and Westcarr notched his fourth for the club with a close-range header.
Paterson rounded off the win with number four from Westcarr's 73rd-minute pass.