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