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