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