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