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