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