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