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