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