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