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)(25,26,30,32)(27,34,37,31)(28,38,33,29)(35,36,39,40)(2,6)(7,8)(9,11)(10,14)(12,18)(13,17)(15,21)(16,22)(19,24)(20,23)(25,27)(26,31)(28,35)(29,36)(30,37)(32,34)(33,39)(38,40) involution — undirected(1,3,5,4)(2,7,6,8)(10,15)(11,17)(16,19)(18,23)(25,28,29,26,30,33,38,32)(27,35,36,31,37,39,40,34)(1,4,5,3)(2,8,6,7)(11,17)(14,21)(18,23)(22,24)(25,29,30,38)(26,28,32,33)(27,36,37,40)(31,35,34,39)(9,12,13,20)(10,16,15,19)(11,18,17,23)(14,22,21,24)(27,37)(31,34)(35,39)(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.