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