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