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