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