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