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