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