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