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