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