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