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