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