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