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