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