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