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