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