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