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