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