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