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