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