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