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