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