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