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