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