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