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