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