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