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)(23,24)(3,7)(5,8)(9,10,14,11)(12,15,20,17)(13,16,22,18)(19,23,21,24)(25,26)(27,31)(28,32)(29,33)(30,35)(34,40)(36,39)(37,38)(1,2)(3,5)(4,6)(7,8)(25,27)(26,30)(28,34)(29,35)(31,33)(32,39)(36,38)(37,40) involution — undirected(9,11,14,10)(12,15,20,17)(13,16,22,18)(19,24,21,23)(25,27)(26,31)(28,36)(29,35)(30,33)(32,39)(34,38)(37,40)(1,3)(2,5)(4,7)(6,8)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,26)(27,30)(28,37)(29,33)(31,35)(32,38)(34,40)(36,39)(1,2)(3,5)(4,6)(7,8)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)(25,28)(26,32)(27,34)(29,38)(30,39)(31,40)(33,37)(35,36)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.