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