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