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