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