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)(12,18,26,36)(13,17,14,19)(21,30,23,31)(22,29,38,39)(25,34,37,40)(27,33,28,35)(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)(22,28)(26,37)(27,38)(29,35)(33,39)(36,40) involution — undirected(10,17,20,19)(11,21,24,23)(12,26)(18,35,36,33)(22,25,38,37)(27,28)(29,39)(34,40)(1,3,5,4)(2,6,7,8)(1,4,5,3)(2,6,7,8)(9,12,14,28,15,26,13,27)(10,18,19,35,20,36,17,33)(11,22,23,25,24,38,21,37)(16,29,31,34,32,39,30,40)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.