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