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