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)(11,13)(12,20)(14,15)(16,18)(17,21)(19,24)(22,23)(25,26,31,32)(27,35,36,33)(28,38,37,34)(29,30,39,40)(2,5)(6,7)(10,15)(12,21)(13,16)(19,22)(26,32)(27,36)(29,39)(34,38) involution — undirected(1,2)(3,6)(4,5)(7,8)(10,15)(11,18)(17,20)(19,22)(25,27,31,36)(26,33,32,35)(28,29,37,39)(30,38,40,34)(1,3,4,8)(2,6,5,7)(9,11,14,18)(10,16,15,13)(12,22,21,19)(17,23,20,24)(25,28,31,37)(26,34,32,38)(27,29,36,39)(30,35,40,33)(9,12,14,21)(10,17,15,20)(11,19,18,22)(13,23,16,24)(25,29)(26,30)(27,37)(28,36)(31,39)(32,40)(33,38)(34,35)(9,13,14,16)(10,18,15,11)(12,23,21,24)(17,22,20,19)(25,30)(26,29)(27,38)(28,35)(31,40)(32,39)(33,37)(34,36)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.