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