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