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