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