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)(12,13)(14,19)(15,17)(18,24)(20,21)(22,23)(25,26)(27,34)(28,31)(29,36)(30,33)(32,38)(35,39)(37,40)(1,3,5,8)(2,6,4,7)(9,11,15,14)(10,16,17,19)(12,20,18,22)(13,21,24,23)(25,27)(26,30)(28,34)(29,35)(31,33)(32,39)(36,37)(38,40)(10,17)(12,18)(16,19)(20,22)(26,28)(27,33)(32,36)(35,40) involution — undirected(9,12,15,18)(10,13,17,24)(11,20,14,22)(16,21,19,23)(25,28,31,26)(27,34,33,30)(29,36,38,32)(35,37,40,39)(1,2,5,4)(3,6,8,7)(9,13)(10,18)(11,21)(12,17)(14,23)(15,24)(16,22)(19,20)(25,29)(26,32)(27,35)(28,36)(30,39)(31,38)(33,40)(34,37)(1,4,5,2)(3,7,8,6)(9,14,15,11)(10,19,17,16)(12,22,18,20)(13,23,24,21)(25,30,31,34)(26,33,28,27)(29,37,38,39)(32,35,36,40)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.