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)(25,26,31,33)(27,35,30,32)(28,34,38,29)(36,40,39,37)(1,3,6,7)(2,4,5,8)(11,17)(15,21)(18,23)(22,24)(25,27,31,30)(26,32,33,35)(28,36,38,39)(29,40,34,37)(1,2,6,5)(3,8,7,4)(10,14)(15,21)(16,19)(22,24)(26,33)(28,38)(32,35)(36,39)(1,4)(2,7)(3,5)(6,8)(9,10)(11,15)(12,16)(13,14)(17,21)(18,22)(19,20)(23,24)(25,28)(26,34)(27,36)(29,33)(30,39)(31,38)(32,37)(35,40) involution — undirected(1,4)(2,3)(5,7)(6,8)(9,11)(10,15)(12,18)(13,17)(14,21)(16,22)(19,24)(20,23)(25,29,31,34)(26,28,33,38)(27,37,30,40)(32,39,35,36)(1,5,6,2)(3,8,7,4)(9,12,13,20)(10,16,14,19)(11,18,17,23)(15,22,21,24)(25,30,31,27)(26,35,33,32)(28,39,38,36)(29,37,34,40)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.