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