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