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