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