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