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