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