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