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