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