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