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