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