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