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