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