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