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