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