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