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