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