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