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