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