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