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