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