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