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