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