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)(11,15)(12,19)(13,14)(16,20)(17,21)(18,24)(22,23)(25,26)(27,35)(28,33)(29,34)(30,32)(31,36)(37,40)(38,39) involution — undirected(1,3,4,8)(2,5,6,7)(10,14)(15,21)(16,19)(22,24)(25,27)(26,31)(28,37)(29,38)(30,36)(32,35)(33,39)(34,40)(3,8)(5,7)(9,11)(10,15)(12,18)(13,17)(14,21)(16,22)(19,24)(20,23)(26,32)(31,35)(33,34)(39,40) involution — undirected(2,6)(5,7)(10,14)(11,17)(16,19)(18,23)(26,32)(27,36)(33,34)(37,38) involution — undirected(9,12,13,20)(10,16,14,19)(11,18,17,23)(15,22,21,24)(25,28,30,29)(26,33,32,34)(27,37,36,38)(31,39,35,40)(25,29,30,28)(26,34,32,33)(27,38,36,37)(31,40,35,39)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.