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