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