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