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