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