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)(11,20)(12,17)(13,16)(14,18)(15,19)(21,22)(23,24)(25,26,30,34)(27,31,37,35)(28,38,39,32)(29,33,36,40)(3,7)(5,8)(9,11,15,13)(10,16,19,20)(12,21,18,23)(14,22,17,24)(25,27)(26,31)(28,29)(30,37)(32,40)(33,38)(34,35)(36,39)(1,2)(3,5)(4,6)(7,8)(25,26)(27,35)(28,32)(29,33)(30,34)(31,37)(36,40)(38,39) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,12)(10,17)(11,21)(13,23)(14,19)(15,18)(16,24)(20,22)(25,28,30,39)(26,32,34,38)(27,36,37,29)(31,33,35,40)(1,2)(3,5)(4,6)(7,8)(9,13,15,11)(10,16,19,20)(12,23,18,21)(14,22,17,24)(25,26)(27,31)(28,32)(29,40)(30,34)(33,36)(35,37)(38,39)(9,14,15,17)(10,18,19,12)(11,22,13,24)(16,23,20,21)(25,29,30,36)(26,33,34,40)(27,28,37,39)(31,38,35,32)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.