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