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