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