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