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