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