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