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