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