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