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