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