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