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