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)(11,16)(12,18)(13,21)(14,15)(17,22)(19,20)(23,24)(25,26,30,31)(27,29,33,39)(28,35,36,32)(34,40,37,38)(2,5)(6,7)(10,15)(11,18)(17,21)(19,24)(26,31)(27,33)(28,36)(38,40) involution — undirected(1,2)(3,6)(4,5)(7,8)(10,15)(11,18)(13,22)(20,23)(27,33)(29,39)(34,37)(38,40) involution — undirected(1,3,4,8)(2,6,5,7)(9,11,14,18)(10,16,15,12)(13,19,22,24)(17,23,21,20)(25,27,30,33)(26,29,31,39)(28,37,36,34)(32,40,35,38)(9,12,14,16)(10,11,15,18)(13,20,22,23)(17,19,21,24)(25,28,30,36)(26,32,31,35)(27,34,33,37)(29,38,39,40)(9,13,14,22)(10,17,15,21)(11,19,18,24)(12,20,16,23)(25,29)(26,33)(27,31)(28,38)(30,39)(32,37)(34,35)(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.