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)(11,15)(12,13)(14,16)(18,22)(19,20)(26,30)(27,33)(32,37)(34,39) involution — undirected(1,3,5,6)(2,4,7,8)(9,11,13,16)(10,14,12,15)(17,18,21,22)(19,24,20,23)(27,33)(31,36)(34,39)(38,40)(9,11)(10,14)(12,15)(13,16)(17,19,21,20)(18,23,22,24)(25,26,29,30)(27,31,33,36)(28,32,35,37)(34,38,39,40)(1,2)(3,4)(5,7)(6,8)(9,11)(10,15)(12,14)(13,16)(17,18)(19,23)(20,24)(21,22)(25,27,29,33)(26,31,30,36)(28,34,35,39)(32,38,37,40)(1,4)(2,6)(3,7)(5,8)(9,12,13,10)(11,15,16,14)(17,20,21,19)(18,23,22,24)(25,28,29,35)(26,32,30,37)(27,34,33,39)(31,38,36,40)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.