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