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