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