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