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