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