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