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