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