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