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