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