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