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