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)(11,20)(12,24)(13,27)(14,31)(15,19)(16,23)(17,29)(18,25)(21,36)(22,33)(26,34)(28,32)(30,40)(35,39)(37,38) involution — undirected(2,6)(7,8)(9,11)(10,16)(12,25)(13,21)(14,22)(15,23)(17,34)(18,33)(19,20)(24,31)(26,39)(27,38)(28,29)(30,37)(32,35)(36,40) involution — undirected(1,3,5,4)(2,7,6,8)(9,12,25,11,15,22,14,23)(10,16,31,33,19,20,18,24)(13,28,39,37,30,26,29,21)(17,34,40,38,35,32,27,36)(1,4,5,3)(2,8,6,7)(9,13,14,29,15,30,25,39)(10,17,18,27,19,35,31,40)(11,21,12,26,23,37,22,28)(16,32,24,38,20,34,33,36)(2,6)(7,8)(9,14,15,25)(10,18,19,31)(11,22,23,12)(13,29,30,39)(16,33,20,24)(17,27,35,40)(21,28,37,26)(32,36,34,38)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.