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