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)(11,19)(12,22)(13,23)(14,18)(15,16)(17,20)(21,24)(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)(9,11,14,15)(10,16,18,19)(12,20,13,21)(17,22,24,23)(26,31)(27,34)(28,30)(32,39)(35,37)(38,40)(9,12,14,13)(10,17,18,24)(11,20,15,21)(16,22,19,23)(25,27)(26,32)(28,34)(29,35)(30,37)(31,38)(33,39)(36,40)(2,6)(3,8)(9,13,14,12)(10,17,18,24)(11,21,15,20)(16,22,19,23)(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.