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