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