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