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