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