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