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