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