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)(11,16)(12,17)(13,18)(14,19)(15,20)(21,38)(22,31)(23,32)(24,40)(25,30)(26,34)(27,36)(28,35)(29,37)(33,39)(2,5)(6,7)(9,11,14,21,15,23,27,25)(10,16,19,38,20,32,36,30)(12,26,28,39,13,22,29,24)(17,34,35,33,18,31,37,40)(9,12)(10,17)(11,21)(13,15)(14,29)(16,30)(18,20)(19,37)(23,25)(24,39)(27,28)(31,34)(32,38)(35,36) involution — undirected(1,3,4,8)(2,6,5,7)(9,13,27,28,15,12,14,29)(10,18,36,35,20,17,19,37)(11,22,25,39,23,26,21,24)(16,31,30,33,32,34,38,40)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.