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