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