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