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