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