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