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