One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,7)(9,10,14,18)(11,19,20,37)(12,23,27,38)(13,28,25,17)(15,30,31,21)(16,33,35,26)(22,39,29,34)(24,36,40,32)(1,2)(3,6)(4,5)(7,8)(11,20)(15,31)(19,37)(21,30)(22,29)(24,40)(32,36)(34,39) involution — undirected(9,11,14,20)(10,15,18,31)(12,24,27,40)(13,29,25,22)(16,34,35,39)(17,36,28,32)(19,38,37,23)(21,33,30,26)(2,5)(6,8) involution — undirected(1,3,4,7)(2,6,5,8)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.