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