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