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