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