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