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