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