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