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