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