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