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