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