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