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