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