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