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