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