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