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