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