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