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