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