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