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