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