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