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