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