One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,6)(7,8)(9,10,14,17)(11,19,22,29)(12,16,25,31)(13,26,27,18)(15,21,30,23)(20,33,35,39)(24,37,38,32)(28,34,40,36)(9,11,14,22)(10,15,17,30)(12,20,25,35)(13,21,27,23)(16,28,31,40)(18,29,26,19)(24,34,38,36)(32,39,37,33)(2,5)(3,8)(6,7)(9,12,14,25)(10,16,17,31)(11,20,22,35)(13,24,27,38)(15,28,30,40)(18,32,26,37)(19,33,29,39)(21,34,23,36)(11,21)(13,27)(15,29)(18,26)(19,30)(20,34)(22,23)(24,38)(28,39)(32,37)(33,40)(35,36) involution — undirected(2,6)(5,7)(10,17)(11,22)(16,31)(18,26)(20,35)(21,23)(32,37)(34,36) involution — undirectedA 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.