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