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)(11,12,19,16)(13,17,22,23)(18,20,21,24)(26,32)(27,28)(30,34)(37,39)(10,15)(12,16)(17,23)(20,24)(25,26)(27,36)(28,33)(29,34)(30,35)(31,32)(37,38)(39,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(25,27,31,28)(26,33,32,36)(29,37,35,39)(30,38,34,40)(3,7)(5,8)(9,11,14,19)(10,16,15,12)(13,21,22,18)(17,20,23,24)(25,28,31,27)(26,33,32,36)(29,37,35,39)(30,40,34,38)(1,3)(2,5)(4,7)(6,8)(9,12,14,16)(10,11,15,19)(13,20,22,24)(17,18,23,21)(25,29,31,35)(26,34,32,30)(27,37,28,39)(33,40,36,38)(1,2)(3,5)(4,6)(7,8)(9,13,14,22)(10,17,15,23)(11,18,19,21)(12,20,16,24)(25,30,31,34)(26,35,32,29)(27,38,28,40)(33,39,36,37)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.