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