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