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