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