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