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)(27,36,38,32)(28,29,33,39)(30,34,37,40)(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)(28,37)(29,34)(30,33)(31,38)(35,36)(39,40) involution — undirected(9,11,15,12)(10,13,16,17)(14,19,23,20)(18,21,24,22)(25,26,31,35)(27,36,38,32)(28,29,33,39)(30,34,37,40)(1,3,5,4)(2,7,6,8)(9,12,15,11)(10,17,16,13)(14,20,23,19)(18,22,24,21)(25,28,31,33)(26,29,35,39)(27,37,38,30)(32,34,36,40)(9,13,15,17)(10,11,16,12)(14,22,23,21)(18,20,24,19)(25,29)(26,33)(27,34)(28,35)(30,32)(31,39)(36,37)(38,40)(1,4,5,3)(2,8,6,7)(9,14,15,23)(10,18,16,24)(11,19,12,20)(13,21,17,22)(25,30,31,37)(26,34,35,40)(27,33,38,28)(29,36,39,32)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.