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