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