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