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