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)(11,14)(12,17)(13,16)(15,20)(18,22)(19,24)(21,23)(25,26)(27,30)(28,33)(29,34)(31,35)(32,37)(36,38)(39,40)(2,3)(6,7)(9,10)(11,14)(12,15)(13,16)(17,20)(18,22)(19,23)(21,24)(26,27)(28,35)(32,34)(36,40) involution — undirected(1,3,5,2)(4,7,8,6)(10,11)(15,17)(16,18)(23,24)(25,27,30,26)(28,33,35,31)(29,34,37,32)(36,39,40,38)(1,4)(2,6)(3,7)(5,8)(9,11,14,10)(12,17,20,15)(13,16,22,18)(19,23,21,24)(25,28)(26,31)(27,33)(29,36)(30,35)(32,38)(34,39)(37,40)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,29,30,37)(26,32,27,34)(28,36,35,40)(31,38,33,39)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)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.