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