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