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