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