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