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