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