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