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