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