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