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