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)(11,16)(12,15)(13,17)(14,19)(18,22)(20,23)(21,24)(25,26,32,35)(27,36,31,30)(28,33,40,37)(29,38,39,34)(1,3,5,8)(2,6,4,7)(25,27,32,31)(26,30,35,36)(28,38,40,34)(29,37,39,33)(9,11)(10,14)(12,18)(13,19)(15,21)(16,17)(20,24)(22,23)(25,28)(26,33)(27,34)(29,36)(30,39)(31,38)(32,40)(35,37) involution — undirected(1,4,5,2)(3,7,8,6)(9,12,13,20)(10,15,17,23)(11,18,19,24)(14,21,16,22)(25,29,32,39)(26,34,35,38)(27,37,31,33)(28,36,40,30)(9,11)(10,16)(12,18)(13,19)(14,17)(15,22)(20,24)(21,23)(25,30,32,36)(26,27,35,31)(28,39,40,29)(33,34,37,38)(9,10)(11,14)(12,15)(13,17)(16,19)(18,21)(20,23)(22,24)(25,31,32,27)(26,30,35,36)(28,38,40,34)(29,33,39,37)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.