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