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