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