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