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