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