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