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