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