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