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