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