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