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