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