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