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