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