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