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