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