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