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