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