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