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