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