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