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