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