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