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