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