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