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