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