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